Adobe After Effects CS4 - Manual (Page 563)

557 USING AFTER EFFECTS CS4
Effects and animation presets
Last updated 12/21/2009
Eran Stern provides a video tutorial on the Creative COW website in which he demonstrates how to use the Caustics
effect with the Wave World effect.
Note: The Caustics effect ignores masks and alpha channels on the layer to which it is applied. You can precompose the
layer with the effect and apply the mask to the precomposition layer, or you can precompose the layer with the mask and
apply the effect to the precomposition layer, depending on what result you want to achieve. (See “
Precomposing, nesting,
and pre-rendering ” on page 60.)
This effect works with 8-bpc color.
Original (upper-left), and with Bottom set to the text layer (lower-left) and Water Surface set to the whirl layer with Surface Opacity set to 0%
(lower-right)
To get the most realistic results from Caustics, render the Bottom layer separately, with Render Caustics enabled and
Surface Opacity at 0. Then precompose, and use the resulting layer as the Bottom layer for another Caustics effect with
Render Caustics off. With this process you can offset, scale, or otherwise manipulate the Bottom layer in the precomposed
composition, and thus simulate lighting that doesn’t come from straight overhead.
More Help topics
“ Common Lighting controls and Material controls ” on page 553
Bottom controls
The Bottom controls specify the appearance of the bottom of the body of water:
Bottom Specifies the layer at the bottom of the body of water. This layer is the image that is distorted by the effect,
unless Surface Opacity is 100%.
Scaling Makes the bottom layer larger or smaller. If the edges of the bottom layer show, because of the refraction of
the light through the waves, scale up the bottom layer. Scaling down is useful for tiling a layer to make a complex
pattern.
Repeat Mode Specifies how a scaled-down bottom layer is tiled. Once uses only one tile, basically turning tiling off.
Tiles uses the traditional tiling method of abutting the right edge of one bottom layer tile to the left edge of another
bottom layer tile. This option works well if the bottom layer contains a repeating pattern, like a logo, that needs to read
a certain way. Reflected abuts each edge of a bottom layer tile to a mirrored copy of the tile. This option can eliminate
a hard edge where the two tiles meet.
If Layer Size Differs Specifies how to handle the bottom layer when it is smaller than the composition.
Blur Specifies the amount of blur applied to the bottom layer. To make the bottom sharp, set this control to 0. Higher
values make the bottom appear increasingly blurry, especially where the water is deeper.